<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        #outer{
            width: 200px;
            height: 200px;
            background-color: #000;

            /* 绝对定位 - 脱离了文档流*/
            position: absolute;
            z-index: -1;

            top: 20px;
            left: 100px;
        }
    </style>
</head>
<body>
    <!-- 参照物 - 父容器 -->
    <div id="outer">

    </div>

    <div>
        <img src="../part01-html/imgs/ya.gif" alt="">
    </div>
</body>
</html>